Date: Mon, 25 May 2009 14:15:48 +0200 From: "Paul B. Mahol" <onemda@gmail.com> To: Sam Leffler <sam@errno.com> Cc: current@freebsd.org Subject: Re: 802.11 monitor mode changes coming Message-ID: <3a142e750905250515i5e6a21b0qe6eee63973efa7b8@mail.gmail.com> In-Reply-To: <4A11A08B.6090309@errno.com> References: <4A11A08B.6090309@errno.com>
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On 5/18/09, Sam Leffler <sam@errno.com> wrote: > The patch here: > > http://people.freebsd.org/~sam/monitor-20090518.patch > > has significant changes to monitor mode operation. Most importantly it > replaces DLT_IEEE802_11 support in net80211 by DLT_IEEE802_11_RADIO and > removes the latter from the underlying device. The upshot is that you > can no longer do: > > tcpdump -i ath0 > > instead you will now need a wlanX ifnet; e.g. > > ifconfig wlan create wlandev ath0 wlanmode monitor channel 6 up > tcpdump -i wlan0 -y IEEE802_11_RADIO > > This addresses the longstanding issue that applications like kismet that > want radiotap data needed to open two ifnets, one to receive data and > one to do channel changes. My main concern is whether losing > DLT_IEEE802_11 support will affect any apps. Those that depend on it > should be easy to change; you just request a different DLT and strip the > radiotap header from tap'd frames (or similar). > > In sweeping the drivers to do these changes I've made radiotap support > more consistent and improved some drivers. Drivers not tested so far: > malo, ipw, wpi, and upgt. I tested iwi and it appears broken in that no > frames are rx'd but I'm not sure I'll look at it before 8.0. > > I plan to commit these changes by the end of the week. It makes ndisulator panic, following stupid patch fix it for me: --- /sys/net80211/ieee80211_radiotap.c 2009-05-25 12:14:29.000000000 +0000 +++ ieee80211_radiotap.c 2009-05-25 12:13:59.000000000 +0000 @@ -102,6 +102,8 @@ struct ieee80211com *ic = vap->iv_ic; struct ieee80211_radiotap_header *th = ic->ic_th; + if (th == NULL) + return; KASSERT(th != NULL, ("no radiotap setup")); /* radiotap DLT for raw 802.11 frames */ -- Paul
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